You'd be better off with a longer servo arm and using the midpoint on your control surface horn. You want to keep as far away from the control surface as you can, while still getting the amount of throw you want. If you are using a computer radio, make sure you go into your dual rates (hi rates) and end points and set them as far as they can go, then limit them mechanically. This will give you the best resolution and least amount of flutter in the system.